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e952805d | 1 | /* |
0c36ec31 JB |
2 | * drivers/gpio/max7301.c |
3 | * | |
4 | * Copyright (C) 2006 Juergen Beisert, Pengutronix | |
5 | * Copyright (C) 2008 Guennadi Liakhovetski, Pengutronix | |
e952805d | 6 | * Copyright (C) 2009 Wolfram Sang, Pengutronix |
0c36ec31 JB |
7 | * |
8 | * This program is free software; you can redistribute it and/or modify | |
9 | * it under the terms of the GNU General Public License version 2 as | |
10 | * published by the Free Software Foundation. | |
11 | * | |
e952805d | 12 | * Check max730x.c for further details. |
0c36ec31 JB |
13 | */ |
14 | ||
e952805d | 15 | #include <linux/module.h> |
0c36ec31 JB |
16 | #include <linux/init.h> |
17 | #include <linux/platform_device.h> | |
18 | #include <linux/mutex.h> | |
19 | #include <linux/spi/spi.h> | |
20 | #include <linux/spi/max7301.h> | |
0c36ec31 | 21 | |
e952805d WS |
22 | /* A write to the MAX7301 means one message with one transfer */ |
23 | static int max7301_spi_write(struct device *dev, unsigned int reg, | |
24 | unsigned int val) | |
0c36ec31 | 25 | { |
e952805d | 26 | struct spi_device *spi = to_spi_device(dev); |
0c36ec31 | 27 | u16 word = ((reg & 0x7F) << 8) | (val & 0xFF); |
e952805d | 28 | |
0c36ec31 JB |
29 | return spi_write(spi, (const u8 *)&word, sizeof(word)); |
30 | } | |
31 | ||
e952805d WS |
32 | /* A read from the MAX7301 means two transfers; here, one message each */ |
33 | ||
34 | static int max7301_spi_read(struct device *dev, unsigned int reg) | |
0c36ec31 JB |
35 | { |
36 | int ret; | |
37 | u16 word; | |
e952805d | 38 | struct spi_device *spi = to_spi_device(dev); |
0c36ec31 JB |
39 | |
40 | word = 0x8000 | (reg << 8); | |
41 | ret = spi_write(spi, (const u8 *)&word, sizeof(word)); | |
42 | if (ret) | |
43 | return ret; | |
44 | /* | |
45 | * This relies on the fact, that a transfer with NULL tx_buf shifts out | |
46 | * zero bytes (=NOOP for MAX7301) | |
47 | */ | |
48 | ret = spi_read(spi, (u8 *)&word, sizeof(word)); | |
49 | if (ret) | |
50 | return ret; | |
51 | return word & 0xff; | |
52 | } | |
53 | ||
0c36ec31 JB |
54 | static int __devinit max7301_probe(struct spi_device *spi) |
55 | { | |
56 | struct max7301 *ts; | |
e952805d | 57 | int ret; |
0c36ec31 | 58 | |
e952805d | 59 | /* bits_per_word cannot be configured in platform data */ |
0c36ec31 | 60 | spi->bits_per_word = 16; |
0c36ec31 JB |
61 | ret = spi_setup(spi); |
62 | if (ret < 0) | |
63 | return ret; | |
64 | ||
65 | ts = kzalloc(sizeof(struct max7301), GFP_KERNEL); | |
66 | if (!ts) | |
67 | return -ENOMEM; | |
68 | ||
e952805d WS |
69 | ts->read = max7301_spi_read; |
70 | ts->write = max7301_spi_write; | |
71 | ts->dev = &spi->dev; | |
0c36ec31 | 72 | |
e952805d | 73 | ret = __max730x_probe(ts); |
c557fa3e | 74 | if (ret) |
e952805d | 75 | kfree(ts); |
0c36ec31 JB |
76 | return ret; |
77 | } | |
78 | ||
de3483b0 | 79 | static int __devexit max7301_remove(struct spi_device *spi) |
0c36ec31 | 80 | { |
e952805d | 81 | return __max730x_remove(&spi->dev); |
0c36ec31 JB |
82 | } |
83 | ||
e952805d WS |
84 | static const struct spi_device_id max7301_id[] = { |
85 | { "max7301", 0 }, | |
86 | { } | |
87 | }; | |
88 | MODULE_DEVICE_TABLE(spi, max7301_id); | |
89 | ||
0c36ec31 JB |
90 | static struct spi_driver max7301_driver = { |
91 | .driver = { | |
e952805d WS |
92 | .name = "max7301", |
93 | .owner = THIS_MODULE, | |
0c36ec31 | 94 | }, |
e952805d WS |
95 | .probe = max7301_probe, |
96 | .remove = __devexit_p(max7301_remove), | |
97 | .id_table = max7301_id, | |
0c36ec31 JB |
98 | }; |
99 | ||
100 | static int __init max7301_init(void) | |
101 | { | |
102 | return spi_register_driver(&max7301_driver); | |
103 | } | |
673c0c00 DB |
104 | /* register after spi postcore initcall and before |
105 | * subsys initcalls that may rely on these GPIOs | |
106 | */ | |
107 | subsys_initcall(max7301_init); | |
0c36ec31 JB |
108 | |
109 | static void __exit max7301_exit(void) | |
110 | { | |
111 | spi_unregister_driver(&max7301_driver); | |
112 | } | |
0c36ec31 JB |
113 | module_exit(max7301_exit); |
114 | ||
e952805d | 115 | MODULE_AUTHOR("Juergen Beisert, Wolfram Sang"); |
0c36ec31 | 116 | MODULE_LICENSE("GPL v2"); |
e952805d | 117 | MODULE_DESCRIPTION("MAX7301 GPIO-Expander"); |